I have uploaded a file Toms house Rules Bombing Chart TOM 30Apr08.xls to Files > Player Designed Charts. It is based on target size in hexes. (I use 1.5" hexes with my 1/300 planes.)
Examples of point targets <1 hex would be a vehicle, parked plane, a small building, etc. Things go up from there; 1 hex would be a battery of AA, a small group of buildings, etc. The rest are for ship or airfield sizes, as I often have ship and airfield targets in my Pacific games.
1/700 scale works great as the ships are 3-to-8 hexes long. Damage points are the number of hexes destroyed if a hit
is made. For now, I have gone cheap on my ships. I took WWII Intel overhead deck views from online and printed them out scaled 1.5"/100' (=1/800 scale). Being flat paper, it is easy to fly the planes over and on them. And yes, I move them 1 hex/3 turns. And they have AA.
I hope you find this useful, and any input is welcome.